Ch.10 - Structure and Synthesis of Alcohols

Wade9th EditionOrganic ChemistryISBN: 9780135213728당신이 사용하는 게 아니라요?교과서 변경

Wade 9th Edition

Ch.10 - Structure and Synthesis of Alcohols

문제 49

10장, 문제 49

Determine the structures of compounds A through G, including stereochemistry where appropriate.

검증된 단계별 안내

Step 1: Analyze the first reaction. The starting material is cyclohexene, which reacts with perbenzoic acid (PhCO3H). This is an epoxidation reaction, where the double bond in cyclohexene reacts with the peracid to form an epoxide. Compound A is cyclohexene oxide.

Step 2: Examine the second reaction. Compound A (cyclohexene oxide) reacts with methylmagnesium bromide (CH3MgBr), a Grignard reagent, followed by acid workup (H3O+). The Grignard reagent attacks the less sterically hindered carbon of the epoxide, opening the ring and forming an alcohol. Compound B is 1-methylcyclohexanol.

Step 3: Consider the third reaction. Compound B (1-methylcyclohexanol) undergoes dehydration in the presence of concentrated sulfuric acid (H2SO4) and heat (Δ). This elimination reaction removes water to form an alkene. Compound C is 1-methylcyclohexene.

Step 4: Analyze the final reaction. Compound C (1-methylcyclohexene) undergoes catalytic hydrogenation in the presence of hydrogen gas (H2) and platinum (Pt). This reaction reduces the double bond in the alkene to form a saturated hydrocarbon. The final product is methylcyclohexane.

Step 5: Ensure stereochemistry is considered where appropriate. In this sequence, stereochemistry is relevant during the epoxide opening and Grignard addition, as the attack occurs at the less hindered side of the epoxide. The final product, methylcyclohexane, does not have stereochemical concerns as it is a symmetric saturated hydrocarbon.

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주요 개념

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Grignard Reagents

Grignard reagents are organomagnesium compounds that react with electrophiles to form carbon-carbon bonds. In this reaction scheme, CH3MgBr acts as a nucleophile, attacking the electrophilic carbon of the carbonyl group in compound A, leading to the formation of a tertiary alcohol in compound B.

Acid-Catalyzed Reactions

Acid-catalyzed reactions involve the use of an acid to facilitate the conversion of reactants into products. In this case, sulfuric acid (H2SO4) is used to promote the dehydration of the alcohol in compound B to form an alkene in compound C, highlighting the importance of acid in organic transformations.

Stereochemistry

Stereochemistry refers to the spatial arrangement of atoms in molecules and the impact of this arrangement on chemical properties and reactions. Understanding stereochemistry is crucial for determining the correct structure of compounds A through G, especially when dealing with chiral centers or geometric isomers that may arise during the synthesis.

관련 실천

교과서 질문

Propose structures for intermediates and products (A) through (D)

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교과서 질문

Compound A (C₇H₁₁Br) is treated with magnesium in ether to give B (C₇H₁₁MgBr), which reacts violently with D₂O to give 1-methylcyclohexene with a deuterium atom on the methyl group (C). Reaction of B with acetone (CH₃COCH₃) followed by hydrolysis gives D (C₁₀H₁₈O). Heating D with concentrated H₂SO₄ gives E (C₁₀H₁₆), which decolorizes two equivalents of Br₂ to give F (C₁₀H₁₆Br₄). E undergoes hydrogenation with excess H₂ and a Pt catalyst to give isobutylcyclohexane. Determine the structures of compounds A through F, and show your reasoning throughout.

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교과서 질문

Vinyl alcohols are generally unstable, quickly isomerizing to carbonyl compounds. Propose mechanisms for the following isomerizations.

(c)

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교과서 질문

Propose structures for intermediates and products (A) through (D).

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교과서 질문

Grignard reagents react slowly with oxetane to produce primary alcohols. Propose a mechanism for this reaction, and suggest why oxetane reacts with Grignard reagents even though most ethers do not.

750

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교과서 질문

Many hunting dogs enjoy standing nose-to-nose with a skunk while barking furiously, oblivious to the skunk spray directed toward them. One moderately effective way of lessening the amount of odor is to wash the dog in a bath containing dilute hydrogen peroxide, sodium bicarbonate, and some mild dish detergent. Use chemical reactions to describe how this mixture helps to remove the skunk spray from the dog. The two major components of skunk oil are 3-methylbutane-1-thiol and but-2-ene-1-thiol.

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